The sky of Tokyo, Calendar, Planets (December, 2017)
The sky of Tokyo
Calendar (December)
| 3 | Mercury at stationary point |
| 4 | Full Moon（This year’s largest Full Moon） |
| 10 | Last Quarter Moon |
| 13 | Mercury at inferior conjunction |
| 14 | Geminid Meteor Shower peaks around 16:00（The best time to observe is after midnight on the morning of the 14th. On the order of 40 meteors per hour are expected. Because there is almost no effect from moonlight and the timing of the maximum is not so bad, conditons are relatively good.) |
| 18 | New Moon |
| 22 | Saturn at conjunction / Winter solstice (Sun’s ecliptic longitude 270°) |
| 23 | Mercury at stationary point / Emperor’s Birthday [Tennou-Tanjyobi] (national holiday) |
| 26 | First Quarter Moon |
The days for the peak activities of the meteor showers are based on the predictions of IMO（International Meteor Organization).
Planets
- Mercury
- At the beginning of the month, Mercury is positioned low in the western sky just after sunset. It reaches inferior conjunction on the 13th, after that it is positioned low in the southeastern sky just before sunrise. At the end of the month, its elevation increases. From December 23 to January 8, 2018, its elevation is over 10 degree at 30 minutes before sunrise as seen from Tokyo. From the 23rd to the 31st, its brightness is 0.4 to -0.2 magnitude.
- Venus
- Venus is positioned low in the eastern sky before sunrise, but its apparent location is close to the Sun, making observation difficult.
- Mars
- From the beginning to the middle of the month, Mars is located in the constellation Virgo and moves east. At the end of the month, it moves into the constellation Libra. It can be seen in the southeastern sky before sunrise. Its brightness is 1.7 to 1.5 magnitude.
- Jupiter
- Located in the constellation Libra, Jupiter can be seen in the southeastern sky before sunrise. Its brightness is -1.7 to -1.8 magnitude.
- Saturn
- Located in the constellation Sagittarius, Saturn is positioned low in the western sky just after sunset during the beginning and middle of the month, but its apparent location is close to the Sun and it is not suited for observation. Saturn reaches conjunction on the 22nd, after that it is positioned low in the eastern sky before sunrise.
Source: Ephemeris Computation Office, NAOJ
With the “Sky Viewer” you can easily explore the appearance of a typical urban night sky (planets and constellations are visible). The Celestial Phenomena section of the glossary explains the planetary phenomena terms: greatest elongation, opposition, conjunction, stationary, etc.